class Student:
    name: None

    def say_hello(self):
        print('Hello😀')

    def introduce_self(self):
        print(F'大家好！我叫{self.name}')

    def greet(self, msg):
        print(F'Hello😀: {msg}')


stu1 = Student()
stu1.name = '周杰伦'
stu1.say_hello()
stu1.introduce_self()
stu1.greet('早上好')

stu2 = Student()
stu2.name = '王俊凯'
stu2.say_hello()
stu2.introduce_self()
stu2.greet('晚上好')
